This invention relates generally to transmissions, and more particularly to methods and apparatus for actuation of continuously variable transmissions.
Transmissions are devices that transform the speed and torque in vehicles using gears, belts, or other drive components. Most transmission designs use discrete speed ratios: low ratios for acceleration, hill climbing, and heavy hauling, and high ratios for higher-speed travel. They use multiple parallel gear sets between input and output shafts. By changing which gear set carries the loads between the shafts, the speed ratio between the input and output shafts is altered.
Transmissions have also been designed that are continuously variable (CVTs). These generally use friction to transfer load from an input shaft to an output shaft. By altering the radial position of friction rollers, belts, or other components, the speed ratio is changed.
Most current CVTs rely upon fixed-design mechanical or hydraulic actuation that cannot be easily changed to respond to differing demands, such as varying vehicle cargo loads and operator performance demands. Accordingly, there is need for CVT actuation systems that are more flexible and adaptable.